Reduce Fuel From Full

[jnmeade]

I added 17.5 gallons of fuel to my CTSW and found that I had 25.5 gallons by sticking the tanks.
I decided to correct the fuel level remaining by taking the tank to full and reducing it by 8.5 gallons.
Whenever I did that, I ended up with a very large negative number.
Can one select Full and then reduce that number by decreasing from the Add button?

 

[dynonsupport]

I added 17.5 gallons of fuel to my CTSW and found that I had 25.5 gallons by sticking the tanks.
I decided to correct the fuel level remaining by taking the tank to full and reducing it by 8.5 gallons.
Whenever I did that, I ended up with a very large negative number.
Can one select Full and then reduce that number by decreasing from the Add button?

Unfortunately, no. To get an accurate fuel level indication, you'll have to re-do the fuel level calibration.

 

[jnmeade]

We may be talking at cross purposes.
I used the buttons on the EMS to go to FULL. Then I tried to use ADD to decrease the fuel level. It went to a large negative number. When I selected FULL again, it showed 34 gallons, which is right.
Are you saying that in doing this I messed up my calibration? I kind of don't think so.
My question was, can you tell the EMS to accept a FULL reading and then decrease from it. I don't think you answered that or I didn't understand it.

 

[dynonsupport]

Sorry - missed the fact that this was a CT, meaning you're talking about the fuel computer numbers, not the fuel gauges. Yes, what you're trying to do should work, and I just spot-checked that it does. If you press ADD, and then make sure that the "ones" column is selected on the menu, then press DEC until you've removed the amount of gallons you are less than full.